From 1fd875f29d0d7429e3a1f55534c44564996b14ff Mon Sep 17 00:00:00 2001
From: Santiago Mola <santiago.mola@datadoghq.com>
Date: Tue, 3 Jun 2025 17:54:38 +0200
Subject: [PATCH] Support attaching tags to telemetry logs

---
 .../trace/api/telemetry/LogCollector.java     | 24 ++++++++++++++++---
 .../telemetry/log/LogPeriodicAction.java      |  1 +
 .../log/LogPeriodicActionTest.groovy          | 15 ++++++++++++
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/internal-api/src/main/java/datadog/trace/api/telemetry/LogCollector.java b/internal-api/src/main/java/datadog/trace/api/telemetry/LogCollector.java
index 80412572dd4..2348843d6da 100644
--- a/internal-api/src/main/java/datadog/trace/api/telemetry/LogCollector.java
+++ b/internal-api/src/main/java/datadog/trace/api/telemetry/LogCollector.java
@@ -9,6 +9,7 @@
 import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
+import javax.annotation.Nullable;
 import org.slf4j.Marker;
 import org.slf4j.MarkerFactory;
 
@@ -34,13 +35,27 @@ private LogCollector() {
     this.rawLogMessages = new ConcurrentHashMap<>(maxCapacity);
   }
 
-  public void addLogMessage(String logLevel, String message, Throwable throwable) {
+  public void addLogMessage(String logLevel, String message, @Nullable Throwable throwable) {
+    addLogMessage(logLevel, message, throwable, null);
+  }
+
+  /**
+   * Queue a log message to be sent on next telemetry flush.
+   *
+   * @param logLevel Log level (ERROR, WARN, DEBUG). Unknown log levels will be ignored.
+   * @param message Log message.
+   * @param throwable Optional throwable to attach a stacktrace.
+   * @param tags Optional tags to attach to the log. These are a comma-separated list, e.g.
+   *     tag1:value1,tag2:value2
+   */
+  public void addLogMessage(
+      String logLevel, String message, @Nullable Throwable throwable, @Nullable String tags) {
     if (rawLogMessages.size() >= maxCapacity) {
       // TODO: We could emit a metric for dropped logs.
       return;
     }
     RawLogMessage rawLogMessage =
-        new RawLogMessage(logLevel, message, throwable, System.currentTimeMillis() / 1000);
+        new RawLogMessage(logLevel, message, throwable, tags, System.currentTimeMillis() / 1000);
     AtomicInteger count = rawLogMessages.computeIfAbsent(rawLogMessage, k -> new AtomicInteger());
     count.incrementAndGet();
   }
@@ -73,13 +88,16 @@ public static class RawLogMessage {
     public final String message;
     public final String logLevel;
     public final Throwable throwable;
+    public final String tags;
     public final long timestamp;
     public int count;
 
-    public RawLogMessage(String logLevel, String message, Throwable throwable, long timestamp) {
+    public RawLogMessage(
+        String logLevel, String message, Throwable throwable, String tags, long timestamp) {
       this.logLevel = logLevel;
       this.message = message;
       this.throwable = throwable;
+      this.tags = tags;
       this.timestamp = timestamp;
     }
 
diff --git a/telemetry/src/main/java/datadog/telemetry/log/LogPeriodicAction.java b/telemetry/src/main/java/datadog/telemetry/log/LogPeriodicAction.java
index c90b103f404..d099e8ba32e 100644
--- a/telemetry/src/main/java/datadog/telemetry/log/LogPeriodicAction.java
+++ b/telemetry/src/main/java/datadog/telemetry/log/LogPeriodicAction.java
@@ -36,6 +36,7 @@ public void doIteration(TelemetryService service) {
           new LogMessage()
               .message(rawLogMsg.message)
               .tracerTime(rawLogMsg.timestamp)
+              .tags(rawLogMsg.tags)
               .count(rawLogMsg.count);
 
       if (rawLogMsg.logLevel != null) {
diff --git a/telemetry/src/test/groovy/datadog/telemetry/log/LogPeriodicActionTest.groovy b/telemetry/src/test/groovy/datadog/telemetry/log/LogPeriodicActionTest.groovy
index aa29acdd6a3..1142594e0fa 100644
--- a/telemetry/src/test/groovy/datadog/telemetry/log/LogPeriodicActionTest.groovy
+++ b/telemetry/src/test/groovy/datadog/telemetry/log/LogPeriodicActionTest.groovy
@@ -21,6 +21,21 @@ class LogPeriodicActionTest extends DDSpecification {
     LogCollector.get().drain()
   }
 
+  void 'log with tags'() {
+    LogMessage logMessage
+
+    when:
+    LogCollector.get().addLogMessage('ERROR', "test", null, 'tag1:value1,tag2:value2')
+    periodicAction.doIteration(telemetryService)
+
+    then:
+    1 * telemetryService.addLogMessage(_) >> { args -> logMessage = args[0] }
+    0 * _
+    logMessage.getLevel() == LogMessageLevel.ERROR
+    logMessage.getMessage() == 'test'
+    logMessage.getTags() == 'tag1:value1,tag2:value2'
+  }
+
   void 'log with datadog throwable'() {
     LogMessage logMessage